From its inception in the course of a program sponsored in the early 1970's by NASA, flat conductor cable power distribution has been extensive evolution. The rudimentary sysrem which emanated from the NASA program made use of cables having three conductors of rectangular cross-section embedded in electrical insulation and effected interconnection of plural such cables by arranging same in mutual abutment in the same plane, i.e., upon a floor. This system employed connectors in the form of straps underlying the cables and having end portions for making insulation-piercing connection with the conductors to be joined. A number of present commercial undercarpet wiring systems follow this approach.
One of the initially introduced commercial undercarpet wiring systems, that of Thomas & Betts Corporation, the assignee of the subject application, involves a method of laying one cable upon another and interconnecting conductors by forming an opening through the conductors, placing a generally L-shaped insulation-piercing connector in the opening and crimping same upon exterior surfaces of the cables to provide interconnection without the connector straddling or otherwise extending over any conductors other than those intended to be interconnected.
In conducting power from a first or main cable run connected to the power feeder of a building to a desired power location, both of the above types of systems extend a second cable, connected as described above to the main cable, to such location and there discretely wire a power outlet pedestal of conventional character to a transition fitting which itself is in insulation-piercing relation with the second cable at such location.
Successively to such initial system versions, the evolution of flat conductor cable power distribution systems embraced an improvement whereby the power outlet pedestal was rendered energized without need for discrete wiring. Pedestals have thus become known which may be applied directly to a single-phase, three-conductor cable, insulation-piercing contacts of such pedestals having internal connectors having insulation-piercing end portions for electrical connection with the cable conductors and other end portions adapted for engagement with the prongs of plugs inserted in pedestal power outlet receptacles. A device of this type is shown in commonly-assigned U.S. Pat. No. 4,479,692, issued on Oct. 30, 1984 and entitled "Receptacle for Flat Multi-Conductor Cable".
In a still further development, such as is shown in commonly-assigned U.S. Pat. No. 4,480,889, issued on Nov. 6, 1984 and entitled "Apparatus and Method for Tapping or Splicing Flat Multi-Conductor Cable", the capability of the above discrete-wire-free pedestal was expanded to also provide for the splicing of another cable to the cable energizing the receptacle. Ninety-degree folding of such additional cable effectively provides a tap connection spatially coincident with the pedestal termination.
Despite the progress of such evolution in flat conductor cable power distribution systems, the installation planner still presently has limited horizon to the extent that one can only realize the advantage of the last two-mentioned improvements after having tapped such pedestal-energizing cable to the main cable run, or having run all three conductor cable branches from the wall. Thus, the only known connections to be made directly to a five conductor flat cable do not encompass the use of insulation-piercing pedestals, be they of splice or non-splice variety, but involve tapping or splicing a second cable thereto. Based on requirements to balance loads among the three phases typically at hand, a minimum of three such non-outlet associated connections need be made in the system installation.
As an additional consideration, the known connections directly to five conductor flat cable are not at visibly determinable locations upon completion of system installation and placement of carpeting atop the system. Thus, the abutting and overlapping connections alluded to at the outset above are not power outlet locations, but are secreted beneath the carpeting in locations only determinable by reference to the installation wiring drawings or, in their absence or departure therefrom, only by removing carpet squares and inspecting the system. In this connection, there remains a vestige of practical difference between undercarpet power distribution systems and the traditional conduit systems, the latter involving cable connections only at power outlet locations, such as junction boxes and pedestals.